Optical Microscope

18 cases · 36 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

Detail focus: Close to the External Surface clear all

Optical Microscope — sub-branches

As polished micrography 7Glyceregia Etched Micrography by OM 2Micrography by OM 2Micrography by OM using A262 Method A 4NH4OH+H2O+H2O2 Etched Micro 2NaOH Electrolytic Etched Micro 1Nital Etched Micrography by OM 15Oxalic Acid Electrolytic Etch 3

Results

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Micrography of the stub end, external side to the top, presenting multiple cracks propagating throught wall.
48
VIEW
ML00168 / Aug.2020
SCC of Austenitic SS Flange Stub End
M - Austenitic Stainless SteelP - Stub EndAp - Chemical IndustryCd - Stress Corrosion
Cm - As polished micrographyDf - Close to the External Surface
Micrography of the longitudinal section of the sleeve, at the interface between the substrate and the first thermal spray layer. The substrate (bottom of the figure) shows a ferritic-austenitic microstructure and detrimental phases that look like sigma. The thermal spray layer (top of the figure) presents the non-etched stainless steel, disposed in layers, with oxides (gray) and voids (black). The substrate is deformed in a thin layer at the interface.
38
VIEW
ML00147 / Aug.2018
WC Layer Detached from a Cast Lean Duplex
M - Lean Duplex Stainless SteelP - Centrifugal CastingAp - ShipCd - Lack of Sealing
Cm - NaOH Electrolytic Etched MicroDf - Close to the External Surface
Micrographic aspect, as polished, of the cast cylinder section at the fracture position (top of the figure), close to the external surface (left side). It is possible to see smaller graphite flakes, interdendritic .
79
VIEW
ML00141 / Jul.2018
Brittle Fracture of a Corroded Gray Cast Iron
M - Gray Cast ironP - CastingAp - EngineCd - Brittle Fracture
Cm - As polished micrographyDf - Close to the External Surface
Micrography of the damaged region close to the external surface, presenting a localized dissolution/corrosion.
58
VIEW
ML00135 / May.2018
MIC of a Non Magnetic Drilling Tool
M - High Mn Austenitic SteelP - Tubular ForgingAp - O&G Well DrillingCd - Pitting Corrosion
Cm - Oxalic Acid Electrolytic EtchDf - Close to the External Surface
Micrography of an axial section of the roller bearing, at the external surface, where the hardness level was about 64 HRc (higher than the limit of 58HRc to 62 HRc).
86
VIEW
ML00131 / Apr.2018
Brittle Failure of a Soft Roller Bearing
M - Wear Resistant SteelP - Roller BearingAp - Mechanical IndustryCd - Heat Treatment Defect
Cm - Nital Etched Micrography by OMDf - Close to the External Surface
Micrography of a transverse section of the tubing in the center of the thickness. Ferritic-pearlitic structure. The structure is fully ferritic in a small extension at the surface, due to a decarburization effect during manufacturing.
26
VIEW
ML00116 / Jan.2018
CMn Steel Structural Tubing 6 mm thick
M - CMn SteelP - Seamless Round ShapeAp - StructureCd - Removed From Service
Cm - Nital Etched Micrography by OMDf - Close to the External Surface
Micrographic detail of a transverse section of the tubing, at the external surface. Ferritic-pearlitic structure. The roughness of the surface is high because the structure was painted and a blasting treatment was probably applied to the surface to improve adherence.
15
VIEW
ML00115 / Jan.2018
CMn Steel Structural Tubing 5 mm thick
M - CMn SteelP - Seamless Round ShapeAp - StructureCd - Removed From Service
Cm - Nital Etched Micrography by OMDf - Close to the External Surface
Micrography of a transverse section of the tubing, at the external surface. Ferritic-pearlitic structure. The roughness of the surface is high because the structure was painted and a blasting treatment was probably applied to the surface to improve adherence.
20
VIEW
ML00114 / Jan.2018
CMn Steel Structural Tubing 8 mm thick
M - CMn SteelP - Seamless Round ShapeAp - StructureCd - Removed From Service
Cm - Nital Etched Micrography by OMDf - Close to the External Surface

More from these cases

ML00168 — SCC of Austenitic SS Flange Stub EndM - Austenitic Stainless SteelP - Stub EndAp - Chemical IndustryCd - Stress Corrosion
Micrography of the stub end close to the external surface, outer diameter in the top of the image, presenting multiple cracks starting fro the surface and propagating into the thickness, through wall.
32
VIEW
ML00168 / Aug.2020
SCC of Austenitic SS Flange Stub End
M - Austenitic Stainless SteelP - Stub EndAp - Chemical IndustryCd - Stress Corrosion
Cm - Oxalic Acid Electrolytic EtchDf - Close to the External Surface
ML00141 — Brittle Fracture of a Corroded Gray Cast IronM - Gray Cast ironP - CastingAp - EngineCd - Brittle Fracture
Micrography of the longitudinal section of the cylinder, at the external diameter (right side of the figure), presenting smaller interdendritic graphite flakes in a ferritic-perlitic matrix.
37
VIEW
ML00141 / Jul.2018
Brittle Fracture of a Corroded Gray Cast Iron
M - Gray Cast ironP - CastingAp - EngineCd - Brittle Fracture
Cm - Nital Etched Micrography by OMDf - Close to the External Surface
Micrographic detail of the painted external surface of the cast cylinder.
26
VIEW
ML00141 / Jul.2018
Brittle Fracture of a Corroded Gray Cast Iron
M - Gray Cast ironP - CastingAp - EngineCd - Brittle Fracture
Cm - As polished micrographyDf - Close to the External Surface
Micrographic aspect of the cast cylinder section at the fracture position (top of the figure), close to the external surface (left side). It is possible to see a change in the graphite morphology and matrix.
27
VIEW
ML00141 / Jul.2018
Brittle Fracture of a Corroded Gray Cast Iron
M - Gray Cast ironP - CastingAp - EngineCd - Brittle Fracture
Cm - Nital Etched Micrography by OMDf - Close to the External Surface
Micrographic detail of the cast cylinder section at the fracture position (top of the figure), close to the external surface (left side), showing smaller and interdendritic flakes in a ferritic-perlitic matrix, but several cracks following the free carbides very close to the surface.
24
VIEW
ML00141 / Jul.2018
Brittle Fracture of a Corroded Gray Cast Iron
M - Gray Cast ironP - CastingAp - EngineCd - Brittle Fracture
Cm - Nital Etched Micrography by OMDf - Close to the External Surface
Micrographic detail of the interdendritic flakes in a ferritic-perlitic matrix, with secondary cracks following the free carbides (very close to the surface).
25
VIEW
ML00141 / Jul.2018
Brittle Fracture of a Corroded Gray Cast Iron
M - Gray Cast ironP - CastingAp - EngineCd - Brittle Fracture
Cm - Nital Etched Micrography by OMDf - Close to the External Surface
ML00135 — MIC of a Non Magnetic Drilling ToolM - High Mn Austenitic SteelP - Tubular ForgingAp - O&G Well DrillingCd - Pitting Corrosion
Micrography of the damaged region close to the external surface, presenting a localized dissolution/corrosion.
53
VIEW
ML00135 / May.2018
MIC of a Non Magnetic Drilling Tool
M - High Mn Austenitic SteelP - Tubular ForgingAp - O&G Well DrillingCd - Pitting Corrosion
Cm - Oxalic Acid Electrolytic EtchDf - Close to the External Surface